JEC COMPOSITES MAGAZINE - Issue #109 - November/December 2016 - 29

viscous resins MANUFACTURING

lt's flow time!

When it comes to pumping and metering, viscous resins pose many
challenges for the aerospace, automotive and renewable energy industries. They are tricky substances to get absolutely right.

anDrew biggs
Technical Director
James lees
Technical Sales Engineer
UK Flowtechnik Ltd

or years, pumps and flowmeters have
been major components in the painting and coating of products. With
technology breakthroughs, more advanced
pumps and flowmeters are now being used
to dispense more complex fluids, such as
special resins, carbon fibres and plastics,
helping manufacturers meet the demand
for faster, lighter, stronger, quieter and more
fuel-efficient products.

Multitple challenges
But viscous resins can pose a number of
challenges for engineers. First, their thick
and sticky consistency means they lose
pressure when pumped through a pipe. Any
bend in the pipe will take away even more
pressure, so it is essential that the pump is
capable of generating enough pressure to allow the viscous resin to flow freely at the desired flow rate.
Secondly, while in a pipe, viscous resins tend
to harden, especially if they contain materials such as aluminium, talc or fibres. Finally,
viscous resins are sensitive to temperature.
If they get too hot, they become runnier and
less thick, too cold and they can set.

Considering these challenges, what is the
type of pump and flowmeter that works
best for viscous resins? Experience shows
that it is best to avoid standard or traditional gear pumps and flowmeters as they
tend to be large, expensive and unreliable, due to their very low output frequencies that can make them difficult to control.
Instead, Flowtechnik's pump of choice is
the German-made Beinlich, which has a
range of positive displacement pumps specifically designed to deal with both high and
low viscosities, thereby making the pumping of thick and sticky resins much easier.
So, what makes the Beinlich so superior?
To start with, Beinlich's pumps operate at a
constant flow and pressure at a given viscosity, so they are able to be extremely accurate,
and are ideal for dispensing and dosing, as
the flow rate will remain proportional to the
speed. The pump's innovative design can
also cope with a wide range of viscosities,
but it is ideally suited to thicker fluids as the
volumetric efficiency actually increases, improving its accuracy.
And finally, as is generally well known,
pumping thicker fluids results in the possibility of creating high system pressures
within the pipework and fittings, but again
the Beinlich pump is more than apt to cope
with pressures up to 200 bar.
No109 November - December 2016

Spot-on ratio
Typically, the dynamic viscosity of viscous resins ranges from one to one million centipoise (cPs). Distilled water is
one centipoise, whereas more viscous
liquids, such as motor oils, are generally 1,000 to 2,000 cPs, and an extremely
thick and sticky resin, like window putty,
is around 1,000,000 cPs. But whatever the
viscosity, when pumping and metering a
viscous resin, it is essential that its constituent materials be mixed to the correct ratio and their combined flow rate must be
spot on.

The German-made Beinlich's pump is ideally suited to
thick fluids

/ jec composites magazine

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #109 - November/December 2016